Apparatus for determining or monitoring a process variable of a medium in a pipeline

ABSTRACT

The invention relates to an apparatus for determining or monitoring a process variable of a medium in a pipeline, which has a predetermined inner cross section, comprising a sensor ( 2 ) and a T-shaped adapter ( 1 ), wherein the adapter has a first portion ( 3 ) and a second portion ( 4 ) arranged essentially perpendicular to the first portion ( 3 ), wherein the first portion ( 3 ) has essentially the same inner cross section (A 1 ) as the pipeline ( 7 ) and wherein the sensor ( 2 ) is so arranged in the second portion ( 4 ) that the end face ( 5 ) of the sensor ( 2 ) facing the medium is flush with the inner surface ( 6 ) of the first portion ( 3 ) of the adapter ( 1 ).

The invention relates to an apparatus for determining or monitoring aprocess variable of a medium in a pipeline, wherein the pipeline has apredetermined inner cross section.

Measuring apparatuses such as sensors, however, also adjustingapparatuses, such as, for example, valves, are widely applied in thefoods and feeds industries. If the measuring apparatuses come in contactwith such materials, they must, for understandable reasons, satisfy thehighest of requirements as regards hygiene.

Potential lodging places for health endangering germs occur in thecontact region with the medium especially at locations, where twocomponents are connected with one another. An example is the location ofinstallation of a sensor, respectively a measuring apparatus, in apipeline. Especially critical in this connection are relatively narrowand small dimensioned, intermediate spaces, respectively gaps, sincethese can be difficult to clean. If a gap is present in the contactregion between sensor and pipeline, the medium can penetrate in the gap;impurities can collect in the gap, and germs can grow. Such measuringapparatuses do not meet the requirements of foods standards, and are,consequently, not permitted for use in the foods field. Equally, theyare not suitable for use in pharmaceutical applications.

An object of the invention is to provide an apparatus, which meets highhygienic requirements.

The object is achieved by an apparatus, which includes a sensor and aT-shaped adapter, wherein the adapter has a first portion and a secondportion arranged essentially perpendicular to the first portion, whereinthe first portion has essentially the same inner cross section as thepipeline and wherein the sensor is so arranged in the second portionthat the end face of the sensor facing the medium is flush with theinner surface of the first portion of the adapter. The solution of theinvention, on the one hand, prevents formation of a gap between thesensor and the pipeline, whereby, on the other hand, also a sufficientlygood cleaning opportunity in the region of the end face, thus in thecontact region of the sensor with the medium, is assured. The end faceof the sensor becomes virtually an integral part of the inner surface ofthe first portion of the adapter.

In an advantageous further development of the apparatus of theinvention, the pipeline has an essentially circularly shaped, innercross section. Furthermore, the end face of the sensor facing the mediumhas essentially the same curvature as the inner surface of the pipeline.

In order that the apparatus of the invention meets highest hygienicrequirements, a preferred embodiment provides that the end face of thesensor facing the medium is arranged gap-freely in the adapter.

The sensor is preferably a conductive or capacitive sensor. Likewise,the sensor can also be a temperature sensor, an ultrasonic sensor, e.g.for flow measurement, a sensor for analytical purposes, a conductivitysensor or some other kind of sensor.

In the case of a capacitive or conductive sensor, a first electrode, anelectrode insulation, a second electrode, a guard and a guard insulationare provided. Alternatively, the capacitive or conductive sensor iscomposed of a first electrode, an electrode insulation, a guard and aguard insulation. In the case of this embodiment, the second electrodeis formed by the adapter. Preferably, the electrode, respectively theelectrodes, are/is composed of the same material as the pipeline and/orthe adapter. Especially, the one or more electrodes are/is composed ofstainless steel. In an advantageous embodiment, the adapter comprises acast part.

Preferably, the apparatus of the invention is manufactured via a methodhaving method steps as follows:

the sensor is pressed into the second portion of the adapter in such amanner that the sensor has a predetermined excess protruding into theadapter relative to the inner cross section of the first portion;

then by a machining method the excess of the sensor protruding into theadapter and/or the inner surface of the first portion of the adapterare/is so machined over that the inner cross section of the firstportion of the adapter and the inner cross section of the pipeline areessentially equal.

After the apparatus of the invention is manufactured in the abovedescribed manner, it is integrated into the pipeline. Integration occursvia usual securement methods, e.g. welding, screwing, etc.

The invention will now be explained in greater detail based on theappended drawing, the figures of which show as follows:

FIG. 1 a a first perspective view of a first embodiment of the adapterof the invention,

FIG. 1 b a second perspective view of the embodiment of the adapter ofthe invention shown in FIG. 1 a,

FIG. 2 a a perspective view of the apparatus of the inventionillustrating the first manufacturing step,

FIG. 2 b a perspective view of the apparatus of the inventionillustrating the second manufacturing step,

FIG. 3 a a perspective view of the embodiment of the apparatus of theinvention shown in FIG. 2 b plus electronics housing,

FIG. 3 b a first perspective view of a form of embodiment of theapparatus of the invention with electronics housing and clampconnections,

FIG. 3 c the form of embodiment shown in FIG. 3 b in a secondperspective view and

FIG. 4 a cross section through the embodiment of the apparatus of theinvention shown in FIG. 2 b.

FIG. 1 a shows a first perspective view of a first embodiment of theadapter 1 of the invention. FIG. 1 b shows a second perspective view ofthe embodiment of the adapter 1 of the invention shown in FIG. 1 a.

Adapter 1 is composed of a first tubular portion 3 and a second tubularportion 4 arranged essentially perpendicular thereto. Via the firstportion 3, the adapter 1 is securable in a pipeline 7. Adapter 1 in theillustrated case is a T-piece. Adapter 1 is a cast part, a turned partor a milled part and serves, moreover, also as a process connection.

In the mounted state, a medium (not shown) is located in the pipeline 7and in the first portion 3 of the adapter 1. The inner diameter D1 ofthe first portion 3 of the adapter 1 and the inner diameter D2 of thepipeline 7 are essentially equal, so that the medium can flow unimpeded.FIGS. 1 a and 1 b show the traversing opening 8 in the second portion 4of the adapter 1. Opening 8 serves for accommodating the sensor 2.

FIGS. 2 a and 2 b are perspective views of the apparatus of theinvention and illustrate the two manufacturing steps for manufacturingthe apparatus of the invention. The sensor 2 is, as shown in FIG. 2 a,so mounted in the traversing opening 2 in the second portion 4 of theadapter 1 that a defined excess 15 protrudes beyond the inner surface 6of the first portion 3 of the adapter 1. The mounting of the sensor 2 inthe second portion 4 occurs preferably via a press fit. In theillustrated case, the sensor 2 is a capacitive sensor.

In a second method step, the excess 15 of the sensor 2 protruding intothe interior of the adapter 1 is removed by a machining method.Preferably, the first portion 3 of the adapter is internally completelymachined over, respectively bored out, including the excess of sensor 2.Especially, the sensor 2 and/or the inner surface 6 of the first portion3 of the adapter 1 are/is so machined over that the inner cross sectionAl of the first portion 3 of the adapter 1 and the inner cross sectionA2 of the pipeline 7 are essentially equal. Therefore, the innerdiameter of the first portion 3 before the second manufacturing stepmust, in given cases, be correspondingly less than the inner diameter D2of the pipeline.

In the finally mounted state, the end face 5 of the sensor 2 isvirtually an integral part of the inner surface 6 of the first portion 3of the adapter 1. The solution of the invention has the advantage thatthe sensor 2 is arranged non-intrusively in the medium and is, thus,mounted flushly and gap-freely in the first portion 3 of the adapter 1.The mounted flush installation means that medium flowing in the pipeline7 is not hindered. Since the installation is gap-free, so that there areno hollow spaces or dead spaces present, the solution is ideallysuitable for hygienic applications.

FIG. 3 a shows the apparatus of the invention provided supplementallywith an electronics housing 9. While the apparatus of the inventionshown in FIG. 3 a is welded into the pipeline 7, in the case of theembodiment shown in FIG. 3 b, two clamp-adapters 10 are welded on thetwo ends of the adapter 1. The clamp-adapters 10 facilitate assembly ofthe apparatus of the invention into the pipeline 7, whereincorresponding clamp-adapters are provided on the pipeline 7. FIG. 3 cshows the form of embodiment shown in FIG. 3 b in a second perspectiveview.

FIGS. 3 a and 4 show an embodiment of the apparatus of the invention, inthe case of which a capacitive sensor 2 is integrated in the adapter 1.As a result of the mutually matching inner-dimensions of the firstportion 3 of the adapter 1 and the pipeline 7, adapter 1 representsvirtually a portion of the pipeline 7. The capacitive sensor mountedflushly in the first portion 3 of the adapter 1 measures, especially,whether medium is located in the pipeline 7 or whether the pipeline 7 isempty.

The capacitive sensor 2 is composed of a centrally arranged, firstelectrode 11, which is insulated from a guard electrode 13 via aninsulator 12. The insulator 12 and the guard electrode 13 surround thefirst electrode 11 concentrically. Preferably, the first electrode 11 ismanufactured of the same material as the adapter, e.g. both arestainless steel. Via an additional insulator 14 arranged concentricallyto the first electrode 11, the guard electrode 13 is insulated from thesecond electrode 15. The second electrode is in the illustrated case theadapter 1. Of course, in connection with the invention, all knownembodiments of capacitive or conductive sensors can be applied.

LIST OF REFERENCE CHARACTERS

-   1 adapter-   2 sensor-   3 first portion-   4 second portion-   5 end face-   6 inner surface-   7 pipeline-   8 opening-   9 electronics housing-   10 securement-   11 first electrode-   12 insulator-   13 guard-   14 insulator-   15 excess

1. Apparatus for determining or monitoring a process variable of amedium in a pipeline, which has a predetermined inner cross section,comprising a sensor (2) and a T-shaped adapter (1), wherein the adapterhas a first portion (3) and a second portion (4) arranged essentiallyperpendicular to the first portion (3), wherein the first portion (3)has essentially the same inner cross section (A1) as the pipeline (7)and wherein the sensor (2) is so arranged in the second portion (4) thatthe end face (5) of the sensor (2) facing the medium is flush with theinner surface (6) of the first portion (3) of the adapter (1). 2.Apparatus as claimed in claim 1, wherein the pipeline (7) has anessentially circularly shaped, inner cross section (A2), and wherein theend face (5) of the sensor (2) facing the medium has the same curvatureas the inner surface (8) of the pipeline (7).
 3. Apparatus as claimed inclaim 1 or 2, wherein the end face (5) of the sensor (2) facing themedium is arranged gap-freely in the adapter (1).
 4. Apparatus asclaimed in claim 1, 2 or 3, wherein the sensor (2) is a conductive orcapacitive sensor.
 5. Apparatus as claimed in claim 4, wherein thecapacitive or conductive sensor (2) is composed of a first electrode(11), an electrode insulation (12), a second electrode, a guard (13) anda guard insulation (14).
 6. Apparatus as claimed in claim 4, wherein thecapacitive or conductive sensor is composed of a first electrode (11),an electrode insulation (12), a guard (13) and a guard insulation (14)and wherein a second electrode is formed by the adapter (1). 7.Apparatus as claimed in claim 4, 5 or 6, wherein the electrode (11)/theelectrodes is/are composed preferably of the same material as thepipeline (7) and/or the adapter (1).
 8. Apparatus as claimed in one ormore of the preceding claims, wherein the adapter (1) is a cast part. 9.Method for manufacture of an apparatus as claimed in at least one ofclaims 1-8, comprising method steps as follows: the sensor (2) ispressed into the second portion (4) of the adapter (1) in such a mannerthat the sensor (2) has an excess (15) protruding into the adapter (1)relative to the inner cross section (Al) of the first portion (3), andthen by a machining method the excess (15) protruding into the adapter(1) and/or the inner surface (A1) of the first portion (3) of theadapter (1) are/is so machined over that the inner cross section (A1) ofthe first portion (3) of the adapter (1) and the inner cross section(A2) of the pipeline (7) are essentially equal.
 10. Method as claimed inclaim 9, wherein after mounting the sensor (2) the adapter (1) isintegrated into the pipeline (7).